UPS x Surge Suppression Joule Rating.

[Anonymous user]

Why the surge suppression portion of all UPSses are almost always lower rated than those from a dedicated surge suppressor? See the exemple:

Backup-UPS RS BR1500

- Surge energy rating: 420 Joules

Backup-UPS ES BE650G:

- Surge energy rating 365 Joules

Even the bigger units from the Smart-UPS series and more professional ones have a lower surge ratings, why? Could it be that these units have a transformer inside and they would limit the surge peak? Some say transformers can do this, some say the surge "arresting" capability of a power transformers is very low, who is telling the truth?

Now the numbers from the APC SurgeArrest PF11VNT3:

Surge energy rating *2030 Joules*
EMI/RFI Noise rejection (100 kHz to 10 mHz) 70 dB
Peak Current Normal Mode 20 kAmps
Peak Current Common Mode 60 kAmps

BTW, why APC "hides" the peak current amps rating and the EMI/RFI noise rejection of the UPSses? Is there an specific reason for that? Why is it less important for the user to know this information when buying an UPS than when buying a dedicated surge protector, since UPSses can work as surge protectors as well?

I know the joule rating is not as important as Let Through Voltage and such, but that still doens't explain me the reason for the lower ratings for UPSses, since they're supposed to give your equipment more protection.

Thanks!

[TheNotoriousKMP_apc]

Rau,

While I understand completely what you're stating, you might want to look at the overall picture.

A UPS's primary feature is the battery back-up, not the surge protection.
A Surge Protector's primary feature is the surge protection.

If you are using a UPS system, and are worried about the surge protection, why not install a hardwired panelmount surge at the service entrance and not worry about anything being affected downstream? This would allow for EXCESSIVE surges/spikes to be harnessed by the panelmount, and IF it happens to go downstream, the UPS's surge surpression is capable of handling the rest.

[Anonymous user · Accepted solution]

Thanks for the tip, but I already have a whole house surge suppressor, one for each phase, but I think I should've put this question differently.

I've read something that says transformers acts a bit like surge suppressors I mean, they can theoretically reduce surges. I don't know how this statement is true, but I wanted to know if the presence of a transformer used for the voltage regulation could suppress part of the surge thus allowing the UPS surge suppressor componentes itself, MOVs and such, be smaller...

I still think APC should at least divulge the filtering numbers for their UPS units and the peak amps sustained by the UPS MOVs, that's not a hard thing to do since other brands do that! The MOV numbers are available on the MOV maker website and running some oscilloscope tests and also judging by the componentes used, capacitors, inductors... they can tell how much filtering the unit is capable of, as far as my scarce knowledge go.

I had to open my UPS to see what components were used. There is I think two "X" capacitors, one inductor coil, 4 "y" capacitors and or 4 or 5 10mm MOVs - I think they are 10mm... The specifications of them I can't recall right now...

Thanks once again!